1) Their IP address matches anything on your list of banned IP addresses
2) They don't have a value for their IP Address

It also logs successful "blocks", so you can see how many people are being blocked by the plugin, and the reason they were "blocked".
Wildcards are also supported so you can specify IP ranges, as well as who IP addresses.

This plugin gives you an easy to use feature, which will allow you to ban THE WHOLE URL of spamming sites. We run several directory sites ourselves, and often have the problem of spammers. They are the most annoying thing on Earth! (wasting *YOUR* time, with junk submissions). Aimed at high traffic sites, including adult directories.

This plugin will enable you to build detailed pages, but ONLY for links that you want. This is a great promotional idea. Can be used for almost any kind of thing, but the main one, being that they PAY for a detailed page! (payments have to be done manually, as this plugin doesn't handle that).

This plugin lets you "sell" top-spots in your directory, in their specific category. For example, if someone is listed in "Games" - but is on the 3rd page, they most likely want to be at the top. With this plugin, you can sell them xx days (i.e 60 days) at the top of the category. In the plugin settings you can define how many spots are allowed to be allocated per category (default is 3). This is to stop the whole of the page being filled up with "priority" listings =)

This plugin gives you users a simple to use "Calendar" system. They can add
their own dates, as well as modify them. It has a nice and clear "list" form for
showing you the things that have been added for any given day. They can even
view a 7 day "span" (i.e the current day, and the next 6 days), the entire month
- and even a whole year (with mini-calendars)

You can also view a full list (i.e just a list of dates, with their
descriptions) - so they can see every single entry (and subject) they have
added. simply clicking on the date.
This version also boasts the option of being able to change the time format (i.e
12 hour or 24 hour), and the ability to turn on/off the "reminders" that
are show on the calendar front page, as well as any other pages you put the code
for showing them on =)

It also now has a calendar_public.cgi script, which lets you show people "public" entries on this script (NB: it still requires people to login, but they can see "shared" entries, instead of only theirs)

This plugin is ideal for site who are listing "rental" availabilities, for properties/venues/etc. There is an admin area for LinkOwners (calendar_admin.cgi) , where they can manage the availability of their listing, and calendar_view.cgi, where users can view the availability of a listing. You can also put a tag on detailed.html, which will show a mini-calendar, with the times highlighted that are booked/available. The colors are CSS based, so should be simple to edit to your site color scheme.